Kinetic growth parameters of different amylolytic and non-amylolytic Lactobacillus strains under various salt and pH conditions

Four Lactobacillus species were studied for their ability to grow at high NaCl concentrations and different initial pH values. Lactobacillus plantarum 541 and A6 could ferment glucose and produce lactic acid in the presence of 8% salt in the medium. For strain 541, the specific rate of lactate production (qlac) and the yield of lactic acid relative to substrate (Yp=s) remained constant, whereas the yield of biomass relative to substrate (Yx=s) decreased up to 6% salt. In contrast, for strain A6, Yp=s decreased up to 6% salt whereas Yx=s did not vary markedly. Combined effects of salt and pH studied through a factorial design did not show significant interaction between salt and pH. The pH was the dominant factor in glucose fermentation for both the strains. Considering overall performance, 4% salt and pH between 6.0 and 6.6 can be taken as appropriate conditions, for the use of both strains as starters in processes where higher salt concentrations are required.